So far, the disc head sliders for computers have been produced by processing block materials of ferrite. In view of the fact that the ferrite material has a low high-frequency permeability, however, it has been recently attempted to reduce the inductance of the disk heads so as to enable them to operate in a wider high-frequency region. It has also been proposed to enable high-rate transfer of data and enhance recording density by reducing the gap between the head and disk.
There have been developed composite materials such as those which contain aluminum oxide and titanium carbide as the main components, or where titanium nitride is allowed to form solid solution partly with titanium carbide. In addition to the above-mentioned main components, MgO, CaO, NiO, etc., which are known to be effective for aluminum oxide, are added to improve the sintering of those materials.
Referring to the thin film magnetic heads, it is especially required that their substrates be free from even minute pores when subjected to super-precision mirror finishing, and be capable of being readily precision-machined. In order to prevent any minute pores from being present on the substrates subjected to such super-precision mirror finishing for these reasons, mixed ceramic powders should be sintered to substantially theoretical density and, moreover, be of an extremely fine structure and strong intergranular bonding forces of ceramic crystals. However, such ceramic sintered bodies encounter considerable difficulty in machining. To provide a solution to this problem, there has already been developed a material which contains aluminum oxide and titanium carbide as the main components, and further includes MgO, NiO, etc. as a machinability-improving agent in an amount of no higher than 5 parts by weight per 100 parts by weight of said main components (see Japanese Patent Kokai Publication No. 57-135772).